The principal use of hydrofluoric acid is

The correct answer is Option 1.

Hydrofluoric acid (HF) is uniquely characterized by its ability to dissolve silica (SiO₂), the primary component of glass. This chemical reaction forms water-soluble fluorosilicates, a process known as etching. This property makes HF indispensable for frosting light bulbs, marking laboratory glassware, and creating decorative patterns on glass surfaces.

• Option 2: Chlorine or hydrogen peroxide are typically used as bleaching agents; HF lacks these properties.
• Option 3: While highly reactive and corrosive, HF is a weak acid in aqueous solution and is not categorized as a primary strong oxidizing agent like fluorine gas or nitric acid.
• Option 4: While HF is used in industrial synthesis (like Teflon), its principal and most distinctive application in chemical contexts remains the etching of glass due to its specific reactivity with silicon dioxide.

Therefore, the specialized ability to corrode silicate materials confirms Option 1 as the most accurate choice.